) A 1.57 kg block is initially at rest on a horizontal surface. A horizontal force F of magnitude 9.68 N and a vertical downward force P are then applied to the block. The coefficients of friction for the block and surface are Us = 0.4 and µk = 0.25. Determine the magnitude of the frictional force acting on the block if the magnitude of P is (a) 4.71 N and (b) 9.42 N (c) If the force F starts to increase gradually from 0 to 9.68 N Plot the graph for the friction force vs time for part (a) and (b).

A box of mass 12 kg standing on horizontal ground is pushed by a horizontal force of 30 N. If the coefficient of friction is 0.25, will the box move?

A 100-lb block is pushed at constant speed for a distance of 20 ft along a level floor by a force that makes an angle of 35° with the horizontal, as shown in Fig. The coefficient of friction between the block and the floor is 0.35. Determine The work done on the block by gravity. F 35°

A 20-kg crate is subjected to force F = (2s2 + 3)N, where s is the displacement in meter. If the coefficient of friction between the surface is 0.20, what is the speed of the crate when it travels 10 m starting from rest? F